Light-emitting diodes (LEDs) are commonly used in various lighting operations. The color appearance of an object is determined, in part, by the spectral power density (SPD) of light illuminating the object. For humans viewing an object, the SPD is the relative intensity for various wavelengths within the visible light spectrum. However, other factors can also affect color appearance. Also, both a correlated color temperature (CCT) of the LED, and a distance of the temperature of the LED on the CCT from a black-body line (BBL, also known as a black-body locus or a Planckian locus), can affect a human's perception of an object. In particular there is a large market demand for LED lighting solutions, such as in retail and hospitality lighting applications, where it is desirable to control both a color temperature and a brightness level of the LEDs.
There are presently two major technologies for color tuning (e.g., white tuning) of LEDs. A first technology is based on white LEDs of two or more CCTs. The second technology is based on a combination of Red/Green/Blue/Amber colors. The first technology simply does not have a capability to tune LEDs in the Duv direction. In the second technology, the color tuning capability is seldom offered as an available function. In those cases, the user is instead usually offered a color wheel based on either Red-Green-Blue (RGB) or Hue-Saturation-Lightness (HSL) models. However, the RGB and HSL models were not designed for general illumination. Both the RGB and HSL model are more appropriate for graphics or photographic applications.
The information described in this section is provided to offer the skilled artisan a context for the following disclosed subject matter and should not be considered as admitted prior art.